Rheostat.



Patented m 9, mm. E. CASE.

RHEOSTAT.

(Application filed Nov. 29, 1897.)

' 2 Sheets-Shee"l l.

No. 677,94l.

(Nu Mum.)

No. 677,94l. Patented July 9, l90l.

- F. E. CASE.

BHEOSTAT.

(Application filed Nov. 29, 1897.) (No Model.) 2 Sheets-Sheet 2.

\A/ITPIEIEEEEI' I (E9 Q9 I 4 I W'RO'W UNITED STATES PATENT EE-roE.

FRANK E. OASE, OF SOHENEOTADY, NEW YORK, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NEIV YORK.

RH EOSTAT.

SPECIFICATION forming part of Letters'lPatent N o. 677 ,9 11, dated July 9, 1901. Application filed November 29, 1897. Serial No. 660,023. (No model.)

To ctZZ whom it may concern:

Beitknown that I, FRANKE. CASE, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Rheostats, (Case No. 580,) of which the following is a specification.

My invention has for its object to provide a fireproof rheostat which has an extended radiating-surface, so that the heat generated therefrom may be quickly dissipated.

In the accompanying drawings, Figure 1 is aside elevation of myimproved rheostat. Fig. 2 is a cross-section on line 2 2 of Fig. l, and Fig. 3 is a plan view of va rheostat made up of a number of plates.

The resistance-conductor consists of a thin flat ribbon A, wound back and forth in a zigzag manner until the required resistance is obtained and preferably made of German silver on account of its maintaining a practically constant resistance under rise in temperature and also on account of its high resistance. Between the turns of the conductor are placed rectangular heat-radiating bars of H011 B, so arranged that they extend slightly beyond the resistance=conductor. Strips of insulation 0 (preferably of some fireproof material-as asbestos, for example) are interposed between the resistance -conductor and the radiating-bars. The radiating-bars have a cross-section much greater than that of the resistance-con ductor-as five or six times, for example-so that the heat generated by current passing through the conductor is readily absorbed. The radiating-bars are wider than the resistance-conductor and project beyond it on both sides, at the same time presenting two extended surfaces to the air for cooling. The resistance-conductors are so disposed that only very small portions of them are exposed to the air. Consequently the radiation at this point is small; but I have found from actual practice that when heavy masses of iron are disposed on each side of a conductor in the manner shown they will absorb heat from the conductor more quickly than when the conductor is exposed to air on all sides. Furthermore, a rheostat so made is entirely fireproof, a very desirable quality in railway-rheostats, which are subjected at times to very hard usage.

The ends of the resistance-conductor are riveted to iron plates D and E. These plates serve as circuit-terminals and also as end plates to hold the resistance-conductor and radiating-bars in place. Each end plate is provided with a boss G, to which a conductor can be secured, and a boss G for connecting two or more resistances either in series or parallel.

In assembling the resistance the conductor A is wound back and forth with a radiatingbar B between each turn or layer until the required resistance is obtained. A temporary clamp is then employed to hold the parts together, and they are given a coat of japan or similar material, after which the ends of the resistance-plate so formed are inserted in slots or grooves formed in supports H, of firebrick or other non-combustible material. The 1 fireproof supports or clamps H are made of molded material, as vitrified brick, made large and strong, so as to withstand the strain when the resistance is inserted in place. A very great advantage is derived from the use of these end supports, for it enables me to dispense with all bolts and small cla1np= ing parts, which in ordinary constructions require to be well insulated. By coating the radiating-bars and asbestos insulating material with japan the bars are prevented from rusting and the insulation protected. By this arrangement I am enabled to make a large saving in the cost of manufacture, and whereas for most purposes the use of German silver has been prohibitory on account of the cost by my construction only a small amount is used, and the cost of the rheostat as a whole compares favorably with other rheostats on the market. I have found by experiment that there is a saving of five dollars a box in the present construction over a similar box made entirely of German silver with air-spaces between turns when the SfllllG'llSO in temperature is permitted.

In Fig. 3 I have shown the rheostat-plates assembled in a cast-metal box composed of two heavy end plates J and K, connected by four side bars I and open on all sides for ventilation. The end plates are provided with sockets M for the reception of the noncombustible resistanee-plate clamps H and and also with feet K, which are adapted to be bolted to some fixed part of the car. Lugs or bosses L extend inwardly from the side bars I to abut against the ends of the firebrick clamp H and make a tight fit with the latter to prevent its vibration and breakage by impact. Extending across the box, parallel with the end plates, are two retainingbars N, which are bolted to the box and Se cure the resistance-plates in place. G and G, as before, are the bosses in which the connections are secured. In assembling the resistance the plates are mounted in the noncombustible clamps and the clamps slipped into the sockets, after which the retainingbars are secured in place.

The number of plates in the rheostat may be varied to suit different conditions by increasing the number of clamps H and the size of the box. The particular way in which the plates are connected forms no part of the present invention, for the arrangement can be widely varied to suit the requirements.

IVhat I claim as new, and desire to secure by Letters Patent of the United States, is-- 1. The combination with a resistance-ribbon wound longitudinally in a zigzag manner, of heat conducting and radiating bars be tween the turns of the ribbon, and two separate incombustible insulating-supports provided with slots for the reception of the plate formed by the ribbon and radiating-bars.

2. The combination with a resistance-ribbon wound longitudinally in a zigzag manner, of heat conducting and radiating bars between the turns of the ribbon, and separate supports of fire-brick which are provided with grooves for the reception of the plate formed by the ribbon and radiating-bars.

8. The combination with a resistance-ribbon wound longitudinally in a zigzag manner, of a heat conducting and radiating bar between the adjacent turns of the ribbon, strips of insulation separating the bars from the ribbon, and two separate incombustible insulating-supports provided with slots for the reception of the plate formed by the ribbon and radiating-bars.

4t. The combination with a resistance-ribbon wound longitudinallyin azigzag manner, of heat conducting and radiating bars between the turns of the ribbon, strips of in sulation between the ribbon and said bars, and fire-brick clamps provided with grooves for the reception of the plate formed by the ribbon, the radiating-bars, and the strips of insulation.

5. In a rheostat-plate, the combination of a resistance-conductor wound back and forth on itself, heat-radiating bars between adjacent turns of the conductor, an insulating medium between the conductor and the bars, and non-combustible clamps adapted to slip over the end of the resistanceplate and hold the parts in place;

6. In a rheostat, the combination of a resistance-conductor wound back and forth on itself, radiating-bars, an insulating medium between the conductor and the bars, and heavy metallic end plates secured to the ends of the conductor, serving as terminals and also to hold the parts of the rheostat together.

7. In a rheostat, the combination of a resistance-conductor wound back and forth on itself, a radiatingbar between the turns of the conductonan insulating medium between the bars and the conductor, heavy end plates acting as terminals and also to hold the resistance-conductor and bars in place, and an insulating-support provided with a groove or slot for the reception of the rheostat-plate.

8. In a rheostat, the combination of a plurality of resistance-plates composed of resistance conductors, radiating bars having a large cross-section, insulating material between the bars and the conductor, a radian ing-space between the resistance-plates, and a non-combustible clamp which forms a common support for the plates.

9. In a rheostat, the combination of a plurality of resistance-plates, each composed of a resistance-conductor and radiating-bars alternating with each other,clamps made of incombustible insulating material which are common to the resistance-plates, radiatingspaces between the plates, and an iron frame for securing the insulating-clamps in place.

10. The combination with aresistance-ribbon wound longitudinally in a zigzag manner, of heat conducting and radiating bars be tween the turns of the ribbon, metallic end. plates which hold the ribbon and bars together, and fire-brick clamps provided with slots for the reception of the sides of the plate formed by the ribbon, the radiating-bars and the end plates.

11. In a rheostat, the combination of a pin-- rality of resistance-plates, each composed of a number of turns of resistance conductor, with heat-radiating bars between each turn, insulating supports for the plates, and a holder or support comprising a cast-metal box having end plates which are secured to gether by side bars.

12. In a rheost-at, the combination of a pinrality of resistance-plates separated from each other by air-spaces, each plate comprising a plurality of turns of resistance-eonductor, with a heat-radiating bar between the turns, non-combustible insulating-clamps for the plates, holders or supports provided with sockets in which the clamps are located, and side bars, for securing the parts together.

13. In a rheostat, the combination of a German silver resistance conductor wound back and forth on itself, with heat-radiating bars made of iron on account of their heatabsorbing properties, located between the conductor-turns.

14. A metallic frame for resistance-plates, which comprises two heavy end plates connected by side bars and open on all sides for ventilation, sockets for the reception of the resistance-plates, and detachable retainingbars for closing the sockets.

15. The combination with a metallic frame open for air-circulation and provided with sockets, of incombustible insulating-clamps fitting the sockets, resistance-plates held in position by said clamps, and detachable bars for retaining said clamps in the sockets.

16. A plurality of plates, each of which is composed of a resistance-ribbon, interposed conducting and radiating bars and heavy metallic end plates, in combination with fireproof insulating-clamps for holding the plates separated from each other, and a metallic frame for holding the clamps in position.

17. A metallic frame for resistance-plates, which comprises end plates and side bars, with sockets for the resistance-plates, and detachable retaining-bars for closing the sockets.

18. A plurality of resistance-plates, each of which is composed of a resistance; ribbon Wound longitudinally in a zigzag manner,- and interposed conducting and radiating bars; in

combination with an incombustible frame which holds the plates separated from each other to provide radiating-spaces.

19. A plurality of resistance-plates, each of which is composed of a resistance ribbon wound longitudinally in a zigzag manner, and interposed conducting and radiating bars; in combination with fire-brick clamps provided with grooves for-the reception of the plates and adapted to separate them by radiatingspaces.

20. A plurality of resistance-plates, each of which is composed of a resistanceribbon wound longitudinallyin a zigzag manner, and interposed conducting and radiating bars; in combination with fire-brick clamps formed with slots for the reception of the plates, said plates being held separated from each other to provide radiating-spaces, and a metallic frame for holding the fire-brick clamps in position. v

In witness whereof I have hereunto set my hand this 18th day of November, 1897.

FRANK E. CASE.

Witnessesf B. B. HULL, W. F. MACDONALD. 

